Sentinel 1a-2a Incorporating an Object-Based Image Analysis Method for Flood Mapping and Extent Assessment

This study presents flood extent extraction and mapping from Sentinel images. Here we suggest an algorithm for extracting flooded areas from object-based image analysis (OBIA) using Sentinel-1A and Sentinel-2A images to map and assess the flood extent from the beginning to one week after the event. This study used multi-scale parameters in OBIA for image segmentation. First, we identified the flooded regions by applying our proposed algorithm on the Sentinel-1A. Then, to evaluate the effects of the flood on each land-use/land cover (LULC) class, Sentinel-2A images is classified using the OBIA after the event. Besides, we also used the threshold method to compare the proposed algorithm applying OBIA to determine the efficiency in computing parameters for change detection and flood extent mapping. The findings revealed the best performance for the segmentation process with an Object Fitness Index (OFI) is 0.92 when the scale parameter of 60 is applied. The results also show that 2099.4 km2 of the study area is flooded at the beginning of the flood. Furthermore, we found that the most flooded LULC classes are agricultural land and orchards with 695.28km2 (32.4%) and 708.63 km2 (33.7%), respectively. In comparison, about 33.9% of the remaining flooded area has occurred in other classes (i.e., fish farm, built-up, bare land and water bodies). The resulting object of each scale parameter was evaluated by Object Pureness Index (OPI), Object Matching Index (OMI), and OFI. Finally, our Overall Accuracy (OA) method incorporated field data using the Global Positioning System (GPS) shows 93%, 90%, and 89% for LULC, flood map (i.e., using our proposed algorithm), and threshold method, respectively

Large Independent Sets in Triangle-Free Planar Graphs

Every triangle-free planar graph on n vertices has an independent set of size at least (n+1)/3, and this lower bound is tight. We give an algorithm that, given a triangle-free planar graph G on n vertices and an integer k>=0, decides whether G has an independent set of size at least (n+k)/3, in time 2^{O(sqrt{k})}n. Thus, the problem is fixed-parameter tractable when parameterized by k. Furthermore, as a corollary of the result used to prove the correctness of the algorithm, we show that there exists epsilon>0 such that every planar graph of girth at least five on n vertices has an independent set of size at least n/(3-epsilon).Comment: 14 pages, 1 figur

The Effect of Brain-Derived Neurotrophic Factor on Periodontal Furcation Defects

This study aimed to observe the regenerative effect of brain-derived neurotrophic factor (BDNF) in a non-human primate furcation defect model. Class II furcation defects were created in the first and second molars of 8 non-human primates to simulate a clinical situation. The defect was filled with either, Group A: BDNF (500 µg/ml) in high-molecular weight-hyaluronic acid (HMW-HA), Group B: BDNF (50 µg/ml) in HMW-HA, Group C: HMW-HA acid only, Group D: empty defect, or Group E: BDNF (500 µg/ml) in saline. The healing status for all groups was observed at different time-points with micro computed tomography. The animals were euthanized after 11 weeks, and the tooth-bone specimens were subjected to histologic processing. The results showed that all groups seemed to successfully regenerate the alveolar buccal bone, however, only Group A regenerated the entire periodontal tissue, i.e., alveolar bone, cementum and periodontal ligament. It is suggested that the use of BDNF in combination with a scaffold such as the hyaluronic acid in periodontal furcation defects may be an effective treatment option

Efect of antiseptic gels in the microbiologic colonization of the suture threads after oral surgery

Te work was supported by the Oral Medicine, Oral surgery and Implantology Unit. School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain.Three diferent bioadhesive gels were evaluated in a double-blind randomized clinical trial in which microbial growth in the suture thread was assessed following post-surgical application of the aforementioned gels. Also assessed in this trial were, the intensity of post-surgical pain as well as the degree of healing of the patients’ surgical wounds. A total of 21 patients (with 42 wisdom teeth) participated in this trial. Chlorhexidine gel, chlorhexidine-chitosan gel, and hyaluronic acid gel were evaluated, with a neutral water-based gel serving as the control agent. The aerobic and facultative anaerobic bacterial recovery on blood agar was lower in the placebo group than in the experimental groups. The most signifcant diference (p=0.04) was observed in the chlorhexidine-chitosan group. in which the growth of Blood Agar and Mitis Salivarius Agar was signifcantly higher than in the placebo group. The intensity of post-surgical pain was very similar among all the groups. Signifcantly better healing rates were observed in the patients treated with chlorhexidine-chitosan gel when compared with those who used the placebo gel (p=0.03), and in particular when compared with those patients who used hyaluronic acid gel (p=0.01). Through our microbiological analyses, we were able to conclude that none of the bioadhesive gels tested resulted in benefcial reductions in the bacterial/fungal populations. However, the healing rates of patients who were treated with chlorhexidine-chitosan were better than those of the patients who used either the placebo gel or the hyaluronic acid gel